As a trend, a recent mobile communication system physically separates a digital signal processing end and a radio signal processing end from an existing base station.
The digital signal processing end transmits transmission data to the radio signal processing end. The radio signal processing end wirelessly transmits a transmission signal, and the digital signal processing end and the radio signal processing end are connected via a serial interface.
In the case of a serial interface, a transmission speed is limited and thus, when transmitting a large amount of data, the interface is overloaded. To solve the above issue, there is a need to further increase the number of base stations or to add a line between the digital signal processing end and the radio signal processing end. However, high cost is necessary to increase the number of base stations or add the line.